Nowadays machines are known for making and dispensing beverages based on coffee, particularly for the professional sector, such as bars, restaurants, hotels and catering businesses.
They substantially comprise a grinder for the coffee beans, a boiler, a pump, and an assembly for dispensing hot water with which a filter, in which the ground coffee is placed and pressed, can be associated in a downward region.
Therefore once the coffee has been ground, it is pressed in the filter holder which in turn is coupled to the dispenser assembly and then the pump is actuated to dispense the hot water, thus obtaining the infusion.
The coffee that is obtained can vary in its organoleptic characteristics as a function for example of the quantity of ground coffee used, of the degree of grinding, of the level of pressure used, of the time in which the water is dispensed.
Conventional coffee grinders are constituted by a vertical hopper connected to an underlying grinding assembly, which is usually made up of a pair of grinders arranged in axial alignment with the hopper and usually has a ring for adjusting the degree of grinding.
In such coffee grinders, the weight of the coffee present in the hopper influences the granulometry of the ground coffee since the hopper, when it is full, exerts a certain pressure on the ring for adjusting the grinders, bringing them closer together so as to obtain a finer grinding.
As the pressure decreases, the grinders move apart and the grinding becomes coarser: in this way constancy is lacking in the granulometry obtained from the grinding, and therefore the result in the cup is uneven.
Furthermore, conventional coffee grinders on the market have only one adjustment ring adapted to vary the grain size of the ground coffee; such ring is controlled manually or by way of an electric control, but it is calibrated for only one type of coffee beans, for example espresso coffee, coffee creme, regular or Turkish coffee, which however differ greatly from each other and require changing the granulometry type; substantially, changing the type of coffee beans modifies the result in the cup.
In conventional coffee grinders, furthermore, the turning of the grinders entails an overheating that requires the use of liquid cooling systems which increase the running costs.